Various configurations of control handles exist for deflecting the distal end of a catheter. One form of control handle is the so-called “plunger type” handle that includes a generally cylindrical housing with a plunger extending therefrom. The operator generally grips the housing in the palm of a hand with four fingers and uses the thumb to translate the plunger forward and back relative to the housing along an actuation axis. A pull wire or wires are coupled to the plunger and housing in an arrangement that applies or releases tension in the pull wire(s) as the plunger is translated, thereby causing a controlled deflection of the distal tip of the catheter.
Many operators prefer the plunger type form of catheter control handle. Plunger type control handles do not have to be in a certain rotational orientation within the hand of the operator for operation. Thus, the plunger type handle can be rotated to affect rotation of the catheter body without need for the operator to twist the wrist and hand in uncomfortable positions in order to operate the handle. Also, the position of the plunger relative to the housing provides an indication of the degree of deflection occurring at the distal tip of the catheter. For bi-directional applications, one design challenge posed by the plunger type control handle providing balance between the amount of pull wire taken in and the amount of pull wire released by the control handle. That is, the amount of one wire end taken into the handle should generally be equal to the amount the other wire end released or let out of the handle. This has lead to rather elaborate designs including dual sliders or complicated routing within the handle to effect an equal amount of taken in and released wire.
A control handle that provides balanced intake and release of pull wire in the plunger type form with simplified internals would be welcome.